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Grundfos Instant Hot Water System

Any problems with too much hot water bypassing into the cold line ? Anyone try circulation through a coil alone ? Thanks in advance .


  • Al Letellier
    Al Letellier Member Posts: 781
    Grundfos recirc

    I won one at a trade show and installed it in my home, on a coil at first and now on an indirect. Absolutely no problems to date.

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  • scott337
    scott337 Member Posts: 38
    Not a lot of water moves through this

    Grundfos ComfortMaker moves about a liter per hour of water. Yoru cold water acts as the return line and may get tepid to warm but only for a second or two, not the minute or two that most homes take to get the hot water to the faucet or shower head. Great doorprize! Love these things!
  • This system was covered here before:


    The ones I've installed are working very well although they are not yet approved in the Peoples Republic of MASS. A real energy saver and well made system.

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  • Dave_14
    Dave_14 Member Posts: 17

    I installed one of these units in my home almost 2 years ago. The funny thing about it is that I have found that I continue to have hot water recirc. with the pump being unplugged for the last year+. Seems that the little temperature sensing valve allows or rather enables gravity circulation in my system. Works best in the winter, but still not too shabby in the summer.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    I'll install one

    this Fri. in a home with a VitoCell 79g indirect without a recirc line. The home is only 7 years old and 4000SF, but the plumber didn't do the right thing and install a recirc line to the 4 baths and kitchen. The owner was disturbed when he found out it should have been done during the rough-in, and he would have gladly paid for the extra cost. I'll pipe the new recirc pump from the tank's recirc port into a tee on the DHW supply outlet with a CV between the DHW outlet and the Recirc tee. I'll propably have to install at least 2 diverters under the sinks to make this work.

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  • Sweet
    Sweet Member Posts: 31

    Ive installed a bunch of these systems and really like them. Hot water overtaking the cold for an extended period of time is rare but can happen.Be care ful when installing bypass at fixture where main water valve ties into house system as this can result in some cases in hot water migrating into several fixtures cold side tempering. Rare to see though. Good alternative for retro fit H.W. recirc.
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